Zero Spin Silicon- Quantum Computers, page-38

Moosey - my former post was a more detailed explanation of what I am now repeating - you do not appear to understand that v3 resonant frequency bands overlap at low temperatures and when stripping (as with ²⁹Si) you also get some of the adjacent isotope (in this case ³⁰Si) if their atomic weights are adjacent. LIS's advantage is in scavenging out low assay isotopes NOT removing large assays (like ²⁸Si or ²³⁸U).

In stripping you will also get the adjacent (low assay) isotope (if present) since the v3 frequency bands overlap particularly if the atomic weight is just one removed in atomic weight from the target isotope you wish to strip. Where we are lucky with ²³⁵UF₆ (v3 wavelength 15.916 μm) is that its atomic weight is three removed from ²³⁸UF₆ (v3 wavelength 15.934 μm). This implies that it is very difficult (I would say impossible) for our technology to strip ²³⁴U and/or ²³⁶UF₆ from the ²³⁵UF₆ in RepU - thus (whilst it is also uneconomic) nuclear fuel from RepU (if re-enriched) would contain significant amount of ²³⁴U and ²³⁶UF₆ which implies that not only would it be expensive compared to natural uranium but also low quality. Please note that this is NOT MoX which used chemically reprocessed Pu in UNF (mixed with natural uranium - if you used RepU it would be low quality MoX)) to produce more fissile fuel. Fast reactors are totally different to thermal reactors in that they fission the ²³⁶U, ²³⁸U and also the higher actinides (²³⁹Pu, ²⁴⁰Pu, ²⁴²Pu etc) - that's why the Oklo reactor can further burn spent nuclear fuel (see HERE)